(a) Field of the Invention
The present invention discloses an electric motor being able to be driven by electric power from the power source through the electric motor operative control device to do bi-directional rotation of positive or reverse rotation for driving the input end of the constant directional output transmission device and further through the output end of the constant directional output transmission device to provide constant directional rotation output of different speed change ratio in different directions of driving inputs via the constant directional output transmission device with different speed change ratio for driving the loading wheel trains; wherein the present invention can be applied in electric motor driven carriers such as electric bicycles, electric motorcycles, electric vehicles, or electric driven industry machinery.
(b) Description of the Prior Art
For the speed change output of the conventional electric motor drive system, except for controlling the electric motor to change speed, it usually has to be achieved by CVT or gear shift, which has drawbacks of complicated structures, high costs and low transmission efficiency.